Until recently anyone who needed to repair cavities in his or her teeth ended up with a mouth full of “silver” fillings. Dental amalgam, which has a silver appearance, was the tooth restoration material of choice. Amalgam, a combination of metals including silver, mercury, and other metals, is still used — but today there are other options that mimic the original teeth they are restoring.

You may have read about some people's concerns about the mercury used in dental amalgam. According to the American Dental Association (ADA), scientific studies have found no ill effects arising from using dental amalgam in fillings for adults or children: “While questions have arisen about the safety of dental amalgam relating to its mercury content, the major US and international scientific and health bodies, including the National Institutes of Health, the US Public Health Service, the Centers for Disease Control and Prevention, the Food and Drug Administration and the World Health Organization, among others have been satisfied that dental amalgam is a safe, reliable and effective restorative material.” Dental amalgam is still used for molars (back teeth) that must withstand heavy pressure from chewing.

For teeth that are more visible, materials that look and perform more like the original teeth — and are thus more pleasing in appearance — are now available. Dentistry is now taking a “biomimetic approach” (from words meaning “life mimicking”). The new materials — composite resins and porcelains — look like teeth because in many ways their structure imitates the biologic structure of teeth.

Composite resins are made of a plastic material (methacrylate) combined with fillers made of silica, a form of glass. They are able to bond to natural tooth structure and resemble the dentin, the inner layer of the tooth, which has a porous structure similar to bone.

Dental porcelains are a form of ceramic. They are non-metallic materials formed by the action of heat, like the ceramics used in porcelain cups and bowls. They come in a powder form that is mixed with water, shaped, and then placed in an oven until they reach the proper hardness. The end product is translucent and very hard, resembling the densely packed crystals of calcium that make up a tooth's normal outer layer, the enamel.

The old amalgam fillings required removal of tooth material to prepare a site in which they could be placed. Composite resins and porcelains can be used to treat teeth that have small or large amounts of damage to their natural substance because the materials bond directly to the remaining dentin and enamel. Thus they end up stabilizing and strengthening the restored tooth, as well as providing a natural-looking appearance.